On the Ab Initio DFT + U Calculations of the Physical Properties of a Compound with Strong Electron–Electron Correlations by the Case of KFeS2.

The magnetic and electronic properties of quasi-one-dimensional iron chalcogenide compound KFeS2 have been calculated within two DFT + U approaches based on the simplified LSDA + U approach and rotationally invariant LSDA + U approach. It is shown that the simplified LSDA + U approach with the single parameter correctly describes the magnetic ground state but erroneously predicts the electronic properties. On the other hand, the rotationally invariant LSDA + U approach with two independent parameters U and J provides the correct description of electronic and magnetic properties of KFeS2 at once. By the comparison of ab initio results with experimental data on magnetic ground state and electronic properties, the values of the parameters U and J have been proposed for the correct description of physical properties of KFeS2 within the DFT + U approach. [ABSTRACT FROM AUTHOR]